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How Movies Synchronize the Brains of an Audience

Colored areas indicate brain regions with synchronous activity as people watched a clip of The Good, the Bad, and the Ugly.

Uri Hasson

HOLLYWOOD, California—Picture a movie theater, packed for the opening night of a blockbuster film. Hundreds of strangers sit next to each other, transfixed. They tend to blink at the same time. Even their brain activity is, to a remarkable degree, synchronized.

It's a slightly creepy thought. It's also a testament to the captivating power of cinema, says Uri Hasson, a psychologist at Princeton University. At a recent event hosted by the Academy of Motion Picture Arts and Sciences, Hasson presented his research into what happens inside people's brains when they watch movies. His work got a receptive but somewhat wary reaction from several film makers, including Jon Favreau (Swingers, Iron Man, Chef) and Darren Aronofsky (Pi, The Wrestler, Black Swan).

Why Study Movies?

Every waking second, a torrent of information flows into out brains through our eyes and ears. Scientists who want to understand how the human brain processes that stream to make sense of the world in real-time have a problem: You can't use a 5-ton fMRI scanner to monitor people's brain activity as they go about their lives. Even if you could, each person's experience is so different it would be impossible to interpret the findings.

That's why many vision scientists use simple stimuli they can carefully control in the lab, things like bars of light, bursts of noise, and screens filled with moving dots. But those stimuli don't come anywhere close to mimicking the real-world complexity of the sensory information our brains constantly have to deal with.

Movies are somewhere in between the chaos of reality and a simplified lab experiment, says Princeton psychologist Uri Hasson. They're complex and life-like. But the same clip can be shown to different people, and quantified frame-by-frame to study visual elements like color and motion, as well as sound.

In one of his first forays into cinema science, Hasson found that when people watch a clip from the classic Western,The Good, the Bad, and the Ugly, activity in several brain areas rises and falls at the same time in different individuals. The synched up brain regions included the primary auditory and visual cortex, as well as more specialized regions like the fusiform face area, which is important for (you guessed it) identifying faces, Hasson and colleagues reported in the journal Science in 2004.

More recently, he's been trying to figure out what it is about movies that makes people's brains tick together.

Not all movies, it turns out, have the same mind-melding power. Structured movies that use a lot of cinematic devices—cuts, and camera angles, and carefully composed shots designed to control viewers' attention—do it to a greater extent than movies of unstructured reality. At the Academy event, Hasson showed brain scan data his team collected as people watched several different video clips. When people watched tense bank robbery scene from Dog Day Afternoon, there was a significant correlation in activity across nearly 70 percent of their cortex. "The movie takes over the brain responses of the viewers," Hasson said.

A clip from the improv comedy show Curb Your Enthusiasm, on the other hand, elicited synchrony across less than 20 percent of subjects' cortex. And an unscripted clip of reality—a video the researchers made by simply pointing a camera at a crowd of people watching a concert in a New York City park—elicited synchronous activity across less than 5 percent of subjects' cortex.

Colored areas indicate brain regions whose activity was synchronized as people watched four different video clips, that ranged from highly structured movies (left) to unstructured reality (right). Click the image for a larger version.

Uri Hasson

On the second evening of the two-night event, Aronofsky and his writing partner and sometimes co-producer, Ari Handel, were on stage with the scientists as Hasson presented the results of a small study he'd done with a clip from Black Swan. It comes near the end as Nina, the main character portrayed by Natalie Portman, is unraveling. She hallucinates black feathers poking through the skin on her back. It's an intense scene, and like that of Dog Day Afternoon, it seemed to get nearly 70 percent of the cortex firing in synch across subjects.

"They do look very similar, but it'd be more surprising if they didn't," said Handel, who earned a PhD in neuroscience at New York University before getting into movies. "If you're watching a movie, that's your entire sensorium and your feelings." If people's brains were out of synch during a movie, Handel suggested, that might be a bad sign that their minds were wandering. One person might be thinking about the call they need to make, while another contemplates making a popcorn run.

"It's a scary tool for the studios to have," Aronofsky said. "Soon they'll do test screenings with people in MRIs." The audience laughed, but it didn't seem like he was joking, at least not entirely.

Favreau had been similarly intrigued and wary of the idea of tracking audience engagement with brain scans. "The whole trick of film making is hacking those parts of the brain that keep people entertained," he said. But that's not the only goal for most film makers, he added. "How do you use all this to smuggle in something that's a little more transformative? Ideally, you want to present something a little more elusive than what the statistics at this point can identify."

Hasson readily agrees that his fMRI metrics don't measure the quality of a movie. But he thinks some metrics might come closer than others. For example, he suggests scenes that consistently engage people's frontal cortex (which has roles in abstract thought and other "higher" cognitive functions) or parts of the limbic system (which deals with emotion) may be better indicators of the type of elusive quality Favreau mentioned. Unlike the primary auditory and visual cortex, which track what's happening in a movie frame by frame, some of these other areas seem to be integrating what's happening over many minutes, Hasson says. "They might be responding to more interesting aspects of the movie."

He envisions filmmakers using brain scans to gauge how viewers' brains respond to different aspects of a movie. Does the soundtrack cause people's auditory cortex to synch up? Does an emotional scene take control of their limbic system?

What to do with that information would, of course, be up to the individual filmmaker, Hasson said. The Russian filmmaker Andrei Tarkovsky, whose films were known for their ambiguity and lack of conventional structure, might use it differently, than, say, the documentary filmmaker Michael Moore, who applies conventional cinematic devices and narrative structures to real life topics. "If you want people to think alike and be in synch, you could use this tool," Hasson said. "If you want people to think differently, you could also use it."

This is the second in a series of stories about how scientists are studying cinema for clues about the nature of perception, and how the science might aid film makers as they pursue their art.